Vacuum processing apparatus having a means for preventing counter-pressure between chambers

1. A vacuum processing apparatus having a means for preventing counter-pressure between adjacent chambers, which comprises a process chamber, a transfer chamber, and a load lock chamber, comprising: a cassette chamber installed between the chambers, having slits formed at both opposite side surfaces to serve as a passage of a substrate, and providing a space for receiving slit valves having first and second valve plates moved up and down to open and close the slits; a vent detection part configured to detect a vent process in which a vent gas is injected into each chamber; a cassette chamber constant pressure inducing part comprising first and second bypass lines configured to connect each chamber and the cassette chamber and first and second intermittent valves respectively installed at the first and second bypass lines to control a gas flow through each bypass line, such that the gas injected into each chamber is bypassed into the cassette chamber while the both slits of the cassette chamber are sealed by the first and second valve plates and thus a constant pressure is induced between the chamber in which the vent process is performed and the cassette chamber; and a control part configured to determine whether the vent process or a vacuum process is performed in each chamber through a signal detected from the vent detection part.

2. The vacuum processing apparatus of claim 1 , further comprising a vent valve connected to each chamber to inject the vent gas into each chamber, wherein the vent detection part is a vent valve detecting sensor installed at a side of the vent valve to detect an electric signal for opening and closing the vent valve.

3. The vacuum processing apparatus of claim 1 , wherein the slit valve further comprises a connection member configured to connect the first and second valve plates so that the first and second valve plates are simultaneously driven by one driving means.